Field of the Invention
The present invention relates to a power system, and in particular to a power system which has very low power consumption in a standby operation mode.
Description of Related Art
The commercial power supply device is designated to meet the power required for operation of the electronic device under standby mode and normal mode (or called non-standby mode), when the electronic device operates at normal mode or standby mode, it is easily for the power device including two converters to switch the power outputted therefrom to meet the power required for operation of the electronic device. More particularly, one of the converters is employ in providing a main voltage when the electronic device is in the normal operation mode, and the other converter is employ in providing a standby voltage when the electronic device is in the normal operation mode and the standby operation mode. Briefly, when the electronic device is in the standby mode, one of the converters is switched off to achieve the function of low power consumption.
However, the power supply device having two converters is bulk, and the efficiency thereof in the standby operation mode is poor since one of the converters is inactivated. Therefore it is desirable to use a converter design for the power supply device which operates with a high efficiency not only under normal mode, but also for standby mode.